package com.ywk.pattern._21_singleton._21_7;

//双检锁/双重校验锁
public class Singleton {
    private static class SingletomHolder {
        private final static Singleton instance
                = new Singleton();
    }
    private Singleton() {
    }
    public static final  Singleton getInstance() {

        return SingletomHolder.instance;
    }
}
